Proposal: Type inferred default value

[alrz]

Currently, if you want to use default values you have to specify the exact type for default operator,

public T F<T>(CancellationToken ct = default(CancellationToken)) => default(T);

However, compiler could infer the desirable type from the target,

public T F<T>(CancellationToken ct = default) => default;

#1419 rules can also help to infer the best type for the resultant default value.

[lachbaer]

I think it is better to leave the default keyword as a 'function', when inside a body.

First, it is concise, not one time a 'function' another time a 'keyword';

Second, it is better to always write down, what default is returned; maybe one time it may be the class, the other time it may be a derived class.

verbosity is one of the advantages of C#, just see the 'superfluid' abstract keyword on the before the class keyword, because it is clear that it must be an abstract class, as at least one function inside is abstract - greetings from C++ ;-)

For instanciation, like in the optional parameter above, it could really ease typing and reading the code.

[alrz]

@lachbaer Your argument can be applied to var, verbosity is good as long as it's not reduntant. And this has nothing like what abstract implies. default has been always a keyword and not a "function". And also, you don't need to always omit the type (like what you said, you can use it only for default parameters as a convention), as for var which you can simply prefer verbosity and don't use it. It's more of a preference — you may or may not prefer conciseness.

[lachbaer]

@alrz Don't take me too literal, that's why I put function in hyphens :-)

[alrz]

Moved to dotnet/csharplang#102